The present invention relates to a method and apparatus for increasing the separation capacity of flue gas desulfurization apparatus, especially in power plants, with at least one desulfurization reactor having at least one flue gas channel connected thereto at a bottom portion, whereby the flue gas channel extends essentially horizontally, and the flue gas flows through the desulfurization reactor in a vertical upward direction.
Flue gas desulfurization apparatus of the aforementioned kind are especially known in power plants. The flue gas flows through an essentially horizontally extending flue gas channel from the side into the bottom portion of the desulfurization reactor. The flue gas flow is then deflected into a vertical direction so that it flows through the desulfurization reactor from the bottom to the top. At the inner edge of the reactor inlet the flue gas flow is subjected to a sharp turn so that at this location the flow is separated. Furthermore, the flow path of the flue gas present in the upper portion of the flow gas channel in direction toward the first scrubbing zone of the desulfurization reactor is relatively short, while the flow path of the flue gas within the lower portion of the flue gas channel which is guided into the rearward section of the desulfurization reactor is considerably longer so that the flue gas overall is subjected to very different flow paths during the transport from the flue gas channel into the first scrubbing zone of the desulfurization reactor.
Besides the aforementioned disadvantageous flow separation within the area of the inner edge of the desulfurization reactor inlet, a further disadvantage of the known apparatus is that flue gas portions which are guided into the rearward section of the desulfurization reactor have a substantially longer contact time with the descending lime emulsion flow as compared to the flue gas portion which enters the desulfurization reactor in the area of the inner edge. Measurements have demonstrated that due to the longer contact time of the flue gas in the rearward section of the desulfurization reactor already up to 80% of the sulfur contents are absorbed while the separation degree within the flue gas in the forward section of the reactor is very small because the flue gas entering the desulfurization reactor in the area of the inner edge has only a very short contact time with the descending lime emulsion flow until it reaches the first scrubbing zone of the desulfurization reactor.
In this manner, a strongly unsymmetric distribution of the degree of separation occurs which may not be compensated on the further upward path through the scrubbing zones because of the lack of transverse exchange of the flow.
In order to achieve the overall separation degree which is required by law it is thus necessary to provide a large amount of lime emulsion. Furthermore, it is necessary to install a plurality of scrubbing zones. All these measures together result in a great construction volume of the desulfurization reactor and also in very high energy costs for its operation, since the lime emulsion must be fed into the system at a high pressure and the great construction height of the desulfurization reactor requires great pumping pressures.
It is therefore an object of the present invention to provide a method and an apparatus for increasing the separation capacity of flue gas desulfurization apparatus of the aforementioned kind.